Container for fluids and apparatus for temperature control, e.g. warming, of medical fluids

ABSTRACT

A container for warming fluids comprises an inlet port, an outlet port, a fluid conduit configured for fluidly communicating the inlet and outlet ports, and deflection sections. The fluid conduit has a non-constant maximum width in a direction of fluid flow through the fluid conduit. The deflection sections further comprise an entry section and an exit section, each respective exit section being arranged downstream, in the direction of fluid flow, from each respective entry section. The maximum width of the fluid conduit decreases along the direction of fluid flow through the entry section over a first distance and the maximum width of the fluid conduit increases along the direction of fluid flow through the exit section over a second, different distance. An apparatus for warming fluids in, an extracorporeal blood circuit including, and a blood treatment apparatus including the container are also provided.

PRIORITY CLAIM

The present application is a National Phase of International ApplicationNo. PCT/EP2018/062135, filed May 9, 2018, published as PCT PublicationNo. WO 2018/206718 on Nov. 15, 2018, which claims priority to EPApplication No. 17170551.0, filed May 11, 2017, the entire contents ofeach of which are incorporated herein by reference and relied upon.

TECHNICAL FIELD

The present invention relates to a container for fluids (in particular,but not exclusively, a container for cooling or warming fluids) and toan apparatus for temperature control, e.g. warming or cooling, fluids inan apparatus for extracorporeal blood treatment.

The apparatus for extracorporeal blood treatment includes an apparatusfor fluid temperature control (warming or cooling) that is configured toregulate the temperature of medical fluids, for example blood, incombination with a bag for warming or cooling medical fluids. The bag isinserted into the fluid temperature control apparatus and thetemperature is regulated, for example, by heat being transferred (orremoved) from a heating area of the fluids temperature control apparatusthrough the material of the bag and into (or form) the medical fluidflowing through the bag.

The method for controlling the extracorporeal blood treatment apparatusincludes controlling the temperature of a medical fluid, for exampleblood, using the fluid temperature control apparatus and a bag.

BACKGROUND OF THE INVENTION

In medical applications such as extracorporeal blood treatment it isoften desired to regulate the temperature of medical fluids, for examplein cases where the individual temperature of a medical fluid isimportant for particular chemical or biological reactions to take place,or for treatment to be performed under optimal conditions. Other casesinclude returning blood to a patient that has been withdrawn forextracorporeal treatment (e.g. dialysis, hemofiltration,hemodiafiltration).

In many cases, the flow rate of medical fluid varies over time anddepends on a number of factors including treatment type, patientproperties and condition, topology of the extracorporeal circuit, etc.Regulating the temperature under these varying conditions requires arobust system facilitating reliable treatment and handling of medicalfluids.

U.S. Pat. No. 6,464,666 discloses a fluid warming cassette with astiffening frame structure and an integral handle supporting aparenteral fluid container. The fluid container is desirably thin tominimize heat exchange inefficiencies. The frame structure permits thethin fluid container to be inserted into the narrow space between fixedposition warming plates of a warming unit. The frame structure has aquadrilateral shape with sides and ends. The fluid container isattached, at its periphery to the sides and ends of the frame structure,within the quadrilateral shape. Part of the frame structure is formedinto a handle to assist in both the insertion and removal of thecassette from a warming unit.

U.S. 2008/0262409 discloses a system and method for manufacturing a heatexchanger. The heat exchanger comprises a casing with a serpentinepathway, a membrane enclosed by the casing, an inlet tube or valve forfluid to enter the heat exchanger, and an outlet tube or valve for fluidto exit the heat exchanger. The casing encloses the membrane, whichresides between the casing and the fluid. The exterior casing possessesa wide asymmetrical serpentine pathway and particularly comprises arigid, plastic frame. The frame consists of two halves, where the shapeof the pathway is mirrored on both halves of the frame so that when thehalves are sandwiched together they form a channel. The method comprisesattaching a plurality of tubes or valves to a flexible container,creating an asymmetric passage in a rigid shell, enclosing the flexiblecontainer within the shell, and sealing the shell.

JP 2001120658 discloses a medical heat exchanger bag and method formanufacturing the same by which a liquid is prevented from leakingoutside due to breakage caused by the internal pressure generated whenthe liquid flows in a liquid path, by reducing a load applied to theinside of a bent part of a medical heat exchanger bag. The bag isprovided with a series of elongated channels and a series of bends thatinclude two curved channels for fluid to flow through. Both theelongated and the curved channels have increasing or decreasing diameteralong the direction of fluid flow.

Known designs bags or cassettes have shown problems with potential airretention in the internal conduit. Air retention may be caused to someextent by the presence of low speed areas in the internal conduit, forexample at inlet/outlet sections, and at an outer border of the one ormore bends typically included in the conduit. If the conveyed fluid isblood, then such effects entail the risk of blood clotting. Due to airretention and/or the risk of blood clotting, the operating times ofknown designs are often limited in order to ensure safe and reliabletreatment.

Therefore, there is a need for providing an apparatus for warming fluidsand a corresponding container for fluids that reduces or minimizes airretention and/or the risk of blood clotting in case blood is conveyedthrough the container.

SUMMARY

A general aim of the present invention is to provide an apparatus forcontrolling the temperature of fluids for use in an extracorporeal bloodtreatment apparatus that alleviates or minimizes the above-mentioneddrawbacks.

It is a further aim of the present invention to provide a containersuitable for use with an apparatus for controlling the temperature of(e.g., warming or cooling) fluids that alleviates or minimizes theabove-mentioned drawbacks.

It is a further aim of the present invention to provide a container foruse with an apparatus for controlling the temperature of (e.g., warmingor cooling) fluids that minimizes air retention and/or the risk of bloodclotting by preventing or minimizing the formation of low fluid flowareas in an internal conduit of the container.

It is a further aim of the present invention to provide a container foruse with an apparatus for controlling the temperature of (e.g., warmingor cooling) fluids that minimizes pressure drop and/or risk of hemolysisby preventing or minimizing the formation of high fluid flow areas in aninternal conduit of the container.

It is a further aim of the present invention to provide a container foruse with an apparatus for controlling the temperature of (e.g., warmingor cooling) fluids that minimizes air retention and/or the risk of bloodclotting especially at lower fluid flow rates through the container.This may also entail substantial advantages in applications in whichfluids other than blood are conveyed through the container.

It is a further aim of the present invention to provide a container foruse with an apparatus for warming fluids that minimizes the risk forformation of hot spots by preventing or minimizing the retention of airbubbles in an internal conduit of the container. This may also entailpreventing damage to the fluid (e.g. hemolysis in the case of blood,degasing or chemical decomposition in other cases) and/or to thematerial the container is made of, for example, due to overheating.

It is a further aim of the present invention to provide a container foruse with an apparatus for warming fluids that improves or maximizes heattransfer by preventing the formation of hot spots and/or by minimizingthe retention of air bubbles. This may also entail improving oroptimizing the heat exchange between heating surfaces to the apparatusand the fluid conveyed through the container.

It is a further aim of the present invention to provide a container foruse with an apparatus for controlling the temperature of (e.g., warmingor cooling) fluids that can be manufactured at the same or lower cost asknown containers, while providing one or more of the above advantages.

At least one of the above-indicated aims is attained by a container andan apparatus according to one or more of the appended claims, takensingly or in any combination.

In a 1^(st) independent aspect there is provided a container for fluids,in particular a container for warming or cooling fluids, the containercomprising an inlet port; an outlet port; and a fluid conduit configuredfor putting the inlet port in fluid communication with the outlet portand comprising one or more deflection sections. The fluid conduit has anon-constant maximum width in a direction of fluid flow F through thefluid conduit. At least one of the one or more deflection sectionsfurther comprises an entry section and an exit section, each respectiveexit section being arranged downstream, in the direction of fluid flow,from each respective entry section. The maximum width of the fluidconduit decreases along the direction of fluid flow through the entrysection over a first distance D_(e) and the maximum width of the fluidconduit increases along the direction of fluid flow through the exitsection over a second distance D_(x), the first distance and the seconddistance being different from one another.

In a 2^(nd) aspect according to the 1^(st) aspect, the direction offluid flow F through the fluid conduit is based on a direction from theinlet port towards the outlet port.

In a 3^(rd) aspect according to anyone of the preceding aspects, thefirst distance D_(e) is smaller than the second distance D_(x).

In a 4^(th) aspect according to anyone of the preceding aspects, themaximum width of the fluid conduit decreases along the direction offluid flow F through the entry section from a first width L_(c) to asecond width L_(t).

In a 5^(th) aspect according to the preceding aspect, with

${0.5 \leq \frac{L_{t}}{L_{c}} \leq 0.85},$particularly with

${0.7 \leq \frac{L_{t}}{L_{c}} \leq 0.8},$more particularly with

$\frac{L_{t}}{L_{c}} = {0.75.}$

In a 6^(th) aspect according to anyone of the two preceding aspects, themaximum width of the fluid conduit increases along the direction offluid flow F through the exit section from the second width L_(t) to thefirst width L_(c).

In a 7^(th) aspect according to anyone of the preceding aspects, themaximum width of the fluid conduit decreases non uniformly along thedirection of fluid flow F through the entry section with at least afirst phase and a second phase, the decrease in the first phase and thedecrease in the second phases being different from one another.

In an 8^(th) aspect according to anyone of aspects 1 to 6, the maximumwidth of the fluid conduit decreases along the direction of fluid flow Fthrough the entry section less than linearly in a first phase and morethan linearly in a second phase.

In a 9^(th) aspect according to anyone of the two preceding aspects, thefirst phase covers at least 50% of the first distance D_(e).

In a 10^(th) aspect according to anyone of the preceding aspects, themaximum width of the fluid conduit increases along the direction offluid flow F through the exit section substantially constantly over thesecond distance D_(x).

In an 11^(th) aspect according to anyone of the preceding aspects, thefirst distance D_(e) is between about 0.3 times the maximum width andabout 2.0 times the maximum width, particularly between about 0.5 timesthe maximum width and about 0.7 times the maximum width, more in detailabout 0.6 times the maximum width.

In a 12^(th) aspect according to anyone of the preceding aspects, thesecond distance D_(x) is between about 0.8 times the maximum width andabout 4.0 times the maximum width, particularly between about 1.0 timesthe maximum width and about 2.0 times the maximum width.

In a 13^(th) aspect according to anyone of the preceding aspects, foreach of the one or more deflection sections, the entry section has afirst end and a second end, the first end of the entry section beingupstream, in the direction of fluid flow F, of the second end of theentry section; and the exit section has a first end and a second end,the first end of the exit section being upstream, in the direction offluid flow F, of the second end of the exit section.

In a 14^(th) aspect according to the preceding aspect, the maximum widthof the fluid conduit at the first end of the entry section issubstantially equal to the maximum width of the fluid conduit at thesecond end of the exit section.

In a 15^(th) aspect according to anyone of the two preceding aspects,the maximum width of the fluid conduit at the first end of the entrysection is between about 18 mm and 22 mm, particularly between about 19mm and about 21 mm, and/or the maximum width of the fluid conduit at thesecond end of the entry section is between about 13 mm and 17 mm,particularly between about 14 mm and about 16 mm.

In a 16^(th) aspect according to anyone of the three preceding aspects 1to 14, the maximum width of the fluid conduit at the first end of theentry section is between about 38 mm and 42 mm, particularly betweenabout 39 mm and about 41 mm, and/or the maximum width of the fluidconduit at the second end of the entry section is between about 28 mmand 32 mm, particularly between about 29 mm and about 31 mm.

In a 17^(th) aspect according to anyone of the preceding aspects 13 to15, the maximum width of the fluid conduit at the second end of the exitsection is between about 18 mm and 22 mm, particularly between about 19mm and about 21 mm, and/or the maximum width of the fluid conduit at thefirst end of the exit section is between about 13 mm and 17 mm,particularly between about 14 mm and about 16 mm.

In an 18^(th) aspect according to anyone of the preceding aspects 13,14, 16, the maximum width of the fluid conduit at the second end of theexit section is between about 38 mm and 42 mm, particularly betweenabout 39 mm and about 41 mm, and/or the maximum width of the fluidconduit at the first end of the exit section is between about 28 mm and32 mm, particularly between about 29 mm and about 31 mm.

In a 19^(th) aspect according to anyone of the preceding aspects, eachof the one or more deflection sections further comprises an intermediatesection interposed between the entry section and the exit section.

In a 20^(th) aspect according to the preceding aspect, each respectiveintermediate section has a substantially constant width.

In a 21^(st) aspect according to anyone of aspects 4 to 6, incombination with the preceding aspect, the constant width is equal tothe second width L_(t).

In a 22^(nd) aspect according to anyone of the three preceding aspects,each respective intermediate section is directly adjacent to thecorresponding entry section, particularly the corresponding entrysection being a direct extension of the respective intermediate section.

In a 23^(rd) aspect according to anyone of the four preceding aspects,each respective intermediate section is directly adjacent to thecorresponding exit section, particularly the corresponding exit sectionbeing a direct extension of the respective intermediate section.

In a 24^(th) aspect according to anyone of the five preceding aspects,the intermediate section is provided with an inner radius R₂ calculatedas

${R_{2} = {{\left( {1 - \frac{L_{t}}{L_{c}}} \right) \cdot L_{c}} + \frac{weld}{2}}},$with L_(c)=the maximum width, L_(t)=the width of the intermediatesection (110 i), and weld=width of weld; and/or the ratio

$\frac{R_{2}}{L_{c}}$between the inner radius (R₂) and the maximum width (L_(c)) ranges from0.15 to 0.50, particularly from 0.2 to 0.3, and is more in particularequal to about 0.25.

In a 25^(th) aspect according to anyone of the six preceding aspects,the intermediate section is provided with an outer radius R₃ calculatedas

${R_{3} = {L_{c} + \frac{weld}{2}}},$with with L_(c)=the maximum width, and weld=width of weld.

In a 26^(th) aspect according to anyone of aspects 19 to 25, theintermediate section has an inner edge and an opposite outer edge, theinner edge having a radius smaller than a radius of the outer edge. Eachof the entry section and the exit section has a respective inner edge inextension to the inner edge of the intermediate section. Each of theentry section and the exit section has a respective outer edge inextension to the outer edge of the intermediate section.

In a 27^(th) aspect according to the preceding aspect, the maximum widthof the fluid conduit decreases along the direction of fluid flow Fthrough the entry section substantially due to a directional change ofthe inner edge of the entry section, optionally the outer edge of theentry section continuing substantially straight and/or tangentially inextension from the outer edge of the intermediate section.

In a 28^(th) aspect according to anyone of the two preceding aspects,the maximum width of the fluid conduit increases along the direction offluid flow F through the exit section substantially due to a directionalchange of the inner edge of the exit section, optionally the outer edgeof the exit section continuing substantially straight and/ortangentially in extension from the outer edge of the intermediatesection.

In a 29^(th) aspect according to anyone of aspects 1 to 25, the maximumwidth of the fluid conduit decreases along the direction of fluid flow Fthrough the entry section substantially due to a directional change ofan inner edge of the entry section, and/or an outer edge of the entrysection is substantially straight.

In a 30^(th) aspect according to anyone of aspects 1 to 25 or 29, themaximum width of the fluid conduit increases along the direction offluid flow F through the exit section substantially due to a directionalchange of an inner edge of the exit section, and/or an outer edge of theexit section is substantially straight.

In a 31^(st) aspect according to anyone of the preceding aspects incombination with aspect 19, the intermediate section is provided with adeflection of at least about 90°, particularly about 180°.

In a 32^(nd) aspect according to anyone of the preceding aspects, thefluid conduit further comprises a plurality of connection sections.

In a 33^(rd) aspect according to the preceding aspect, the fluid conduitis provided, along each of the plurality of connection sections, with asubstantially constant maximum width; and/or the fluid conduit is, alongeach of the plurality of connection sections, substantially straight.

In a 34^(th) aspect according to anyone of the two preceding aspects,the fluid conduit is provided with a maximum width along one of theplurality of connection sections equal to a maximum width along eachother of said plurality of connection sections.

In a 35^(th) aspect according to anyone of the three preceding aspects,the plurality of connection sections comprises an inlet sectionconnected to the inlet port and to an adjacent first connection sectionof the plurality of connection sections, the inlet section beingconfigured to provide the fluid conduit with a transition from adiameter of the inlet port to a maximum width of the fluid conduit atthe first connection section, particularly the inlet section includingan inner edge and an outer edge, the inner edge and the outer edge eachforming a respective inlet angle with respect to an axis of the inletport of about 5° to about 30°, more particularly of less than about 15°.

In a 36^(th) aspect according to anyone of the four preceding aspects,the plurality of connection sections comprises an outlet sectionconnected to the outlet port and to an adjacent second connectionsection of the plurality of connection sections, the outlet sectionbeing configured to provide the fluid conduit with a transition from adiameter of the outlet port to a maximum width of the fluid conduit atthe second connection section, particularly the outlet section includingan inner edge and an outer edge, the inner edge and the outer edge eachforming a respective outlet angle with respect to an axis of the outletport of about 25° to about 60°, more particularly of less than about40°.

In a 37^(th) aspect according to anyone of the preceding aspects, thefluid conduit has a meandering or serpentine shape.

In a 38^(th) aspect according to anyone of the preceding aspects, theone or more deflection sections include a number of deflection sections,the number of deflection sections being uneven, optionally the number ofdeflection sections being equal to 1, 3, 5, 7, 9 or 13; particularly thenumber of deflection sections being 1 or 3.

In a 39^(th) aspect according to the preceding aspect, an uneven numberof deflection sections of the one or more deflection sections isarranged opposite to an even number of deflection sections of the one ormore deflection sections.

In a 40^(th) aspect according to anyone of the preceding aspects, theone or more deflection sections include at least three deflectionsections.

In a 41^(st) aspect according to the preceding aspect, at least one ofthe at least three deflection sections is arranged opposite to at leasttwo of the at least three deflection sections.

In a 42^(nd) aspect according to anyone of the preceding aspects, thecontainer further comprises a proximal end and a distal end opposite theproximal end.

In a 43^(rd) aspect according to the preceding aspect, both the inletport and the outlet port are arranged at the proximal end.

In a 44^(th) aspect according to anyone of the two preceding aspects,the container is configured to be inserted, for use, with the distal endfirst into a receptacle of an apparatus for warming or cooling fluids.

In a 45^(th) aspect according to anyone of the preceding aspects, theinlet port is configured for connecting to a fluid inlet line of a bloodtreatment apparatus.

In a 46^(th) aspect according to the preceding aspect, the inlet port isconfigured for receiving medical fluid from the fluid inlet line throughthe inlet port.

In a 47^(th) aspect according to anyone of the preceding aspects, theoutlet port is configured for connecting to a fluid outlet line of ablood treatment apparatus.

In a 48^(th) aspect according to the preceding aspect, the outlet portis configured for releasing medical fluid from the outlet port into thefluid outlet line.

In a 49^(th) aspect according to anyone of the preceding aspects, thecontainer is made from a substantially flexible material, optionally thematerial including one or more of polyurethane (PUR) andpolyvinylchloride (PVC).

In a 50^(th) aspect according to anyone of the preceding aspects, thecontainer comprises a bag, the bag optionally comprising at least afirst and a second film, the first and the second films being sealed toone another.

In a 51^(st) aspect according to anyone of the preceding aspects,particularly during use when liquid is going through the conduit, theconduit exhibits a ratio between the maximum width and a maximum innerheight (w/h) greater than 5, in particular greater than 10.

In a 52^(nd) aspect according to anyone of the preceding aspects, duringuse, the fluid flow inside the conduit is a laminar flow.

In a 53^(rd) independent aspect, there is provided an apparatus forwarming or cooling medical fluids, comprising a receptacle; a heatingregion; a container for warming or cooling medical fluids according toany one of aspects 1 to 52 received in the receptacle; and the heatingregion is configured to contact at least a portion of the container fortransferring heating energy to a fluid flowing through the container.

In a 54^(th) aspect according to the preceding aspect, the heatingregion further comprises a first heating surface and optionally a secondheating surface, the first and optional second heating surfaces beingconfigured to contact first and second surfaces of the container fortransferring heating energy to a fluid flowing through the container viathe first surface and optionally the second surface.

In a 55^(th) aspect according to anyone of the two preceding aspects,the receptacle further comprises an extension configured to receive amatching portion of the bag in order to ensure one or more of: a correctplacement of the container in the receptacle, a correct orientation ofthe container when placed in the receptacle, a correct positioning ofthe container with respect the apparatus for warming or cooling fluids.

In a 56^(th) aspect according to anyone of the three preceding aspects,the receptacle further comprises, alternatively or in combination areference protrusion configured to engage a matching reference openingof the bag; and/or a sensor, e.g. an optical sensor, configured to sensethe presence of a matching portion of the bag in an extension of thereceptacle; in order to ensure one or more of a correct placement of thecontainer in the receptacle, a correct orientation of the container whenplaced in the receptacle, a correct positioning of the container withrespect the apparatus for warming or cooling fluids.

In a 57^(th) independent aspect there is provided an extracorporealblood circuit comprising a blood withdrawal line connectable to an inletof a primary chamber of a filtration unit; a blood return line connectedto an outlet of the primary chamber, the blood lines being configuredfor connection to a cardiovascular system of a patient; optionally adialysis effluent line connected to an outlet of a secondary chamber ofthe filtration unit. The extracorporeal blood circuit further comprisesa container for warming or cooling fluids according to anyone of aspects1 to 52 connected to the blood return line or to the blood withdrawalline.

In a 58^(th) independent aspect there is provided an apparatus forextracorporeal blood treatment comprising a filtration unit having aprimary chamber and a secondary chamber separated by a semi-permeablemembrane; a blood withdrawal line connected to an inlet of the primarychamber; a blood return line connected to an outlet of the primarychamber, the blood lines being configured for connection to acardiovascular system of a patient; optionally a dialysis supply lineconnected to an inlet of the secondary chamber; optionally a dialysiseffluent line connected to an outlet of the secondary chamber; and atleast one pump to move the fluids in the lines; and a control unitdriving the pump. The apparatus further comprises an apparatus forwarming or cooling medical fluid according to any one of aspects 53 to56.

In a 59th independent aspect, optionally according to anyone of theprevious aspects, there is provided a container 100 for fluidscomprising: an inlet port 112, an inlet tubing 111 having a sectiondiameter and being connected to the inlet port 112; an outlet port 116;and a fluid conduit configured for putting the inlet port in fluidcommunication with the outlet port and comprising one or more deflectionsections 110, wherein the fluid conduit has a non-constant maximum widthLc in a direction of fluid flow F through the fluid conduit and a heighth, the section diameter of the inlet tubing being larger than the heighth of the fluid conduit; at least one of the one or more deflectionsections further comprises an entry section 110 e and an exit section110 x, each respective exit section being arranged downstream, in thedirection of fluid flow, from each respective entry section; an inletsection 113 fluidly connecting the inlet tubing 111 with the fluidconduit, wherein the inlet section 113 comprises a first plane and asecond plane, opposite to the first plane, developing from the inlettubing 111 towards the fluid conduit and converging towards the fluidconduit.

In a 60^(th) aspect according to the preceding aspect, the first planeand/or the second plane of the inlet section defines an angle withrespect to a longitudinal extension of a fluid conduit main plane lessthan 20°, particularly included between 2° and 17°.

In a 61^(st) aspect according to the preceding two aspects, the inletsection further includes a terminal portion connecting the first andsecond plane with the fluid conduit, the terminal portion including tworespective layers substantially parallel at a distance substantiallycorresponding to the height h of the fluid conduit, the first plane andthe second plane being connected to a respective layer of the terminalportion.

Further characteristics and advantages of the present invention willbetter emerge from the detailed description that follows of at least anembodiment of the invention, illustrated by way of non-limiting examplein the accompanying figures of the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The description will now follow, with reference to the appended figures,provided by way of non-limiting example, in which:

FIG. 1 schematically represents an extracorporeal blood treatmentapparatus in accordance with an illustrating embodiment.

FIG. 2 shows, schematically and in partially exploded view, an apparatusfor warming fluids in accordance with embodiments of the presentinvention;

FIG. 3 shows a bag for warming fluids in accordance with a prior artdesign;

FIG. 4 shows a bag for an apparatus for warming fluids, the bag being inaccordance with a first embodiment of the present invention;

FIG. 5 shows a deflection section of one or more deflection sections asused in a bag for an apparatus for warming fluids, the bag being inaccordance with a second embodiment of the present invention;

FIG. 6A shows a side view of an inlet section in accordance withembodiments of the present invention;

FIG. 6B shows a perspective view of an inlet section in accordance withembodiments of the present invention;

FIGS. 7A to 7D show fluid flow based on different alternativeembodiments of inlet sections in accordance with embodiments of thepresent invention;

FIG. 8A shows a bag for an apparatus for warming fluids, the bag beingin accordance with another embodiment of the present invention; and

FIGS. 8B and 8C shows details of the bag embodiment of FIG. 8A.

DETAILED DESCRIPTION

FIG. 1 schematically represents an extracorporeal blood treatmentapparatus 1 in accordance with an illustrating embodiment.

An example of an extracorporeal blood treatment circuit 200 isschematically illustrated, but it is noted that the specific structureof the extracorporeal blood treatment circuit 200 is not relevant forthe purposes of the present invention and therefore other and differentcircuits to those specifically shown in FIG. 1 might be used inconsequence of the functional and design needs of each single medicalapparatus (e.g. continuous renal replacement treatments—CRRTtreatments—vs chronic dialysis treatments).

The extracorporeal blood treatment circuit 200 exhibits a dialysis fluidcircuit 32 having a dialysis fluid supply line 8, configured totransport a dialysis liquid from at least one source 14 towards atreatment station 15 where one or more filtration units 2, or dialyzers,operate.

The dialysis fluid circuit 32 further comprises a dialysis effluent line13, configured for the transport of a dialysate liquid (spent dialysateand liquid ultrafiltered from the blood through a semipermeable membrane5) from the treatment station 15 towards an evacuation zone,schematically denoted by 16 in FIG. 1 .

The hydraulic circuit cooperates with a blood circuit 17, alsoschematically represented in FIG. 1 in its basic component parts. Thespecific structure of the blood circuit is also not fundamental to thepresent invention. Thus, with reference to FIG. 1 , a brief descriptionof a possible embodiment of a blood circuit is made, which is howeverprovided purely by way of non-limiting example.

The blood circuit 17 of FIG. 1 comprises a blood withdrawal line 6configured to remove blood from a vascular access 18 and a blood returnline 7 configured to return the treated blood to the vascular access 18.

The blood circuit 17 of FIG. 1 further comprises a primary chamber 3, orblood chamber, of the blood filtration unit 2, the secondary chamber 4of which is connected to the extracorporeal blood treatment circuit 200.

In greater detail, the blood withdrawal line 6 is connected to the inletof the primary chamber 3, while the blood return line 7 is connected tothe outlet of the primary chamber 3.

In turn, the dialysis supply line 8 is connected to the inlet of thesecondary chamber 4, while the dialysis effluent line 13 is connected tothe outlet of the secondary chamber 4.

The filtration unit 2, for example a dialyzer, a plasma filter, ahemofilter, or a hemodiafilter, comprises, as mentioned, the twochambers 3 and 4, which are separated by a semipermeable membrane 5, forexample of the hollow-fiber type or of the plate type.

In an embodiment, the filtration unit (2) may include an adsorptiondevice, such as a plasma filtration adsorption device, a charcoalcolumn, an adsorption device for endotoxin removal for e.g. sepsistreatment; in this embodiment, both a fresh dialysis fluid line and adialysis effluent line to remove spent dialysis fluid may not bepresent.

The blood circuit 17 may also comprise one or more air separators 19 andclamps 20 on both withdrawal and return line.

The extracorporeal blood treatment apparatus 1 comprises one or moreblood pumps 21, for example positive displacement pumps such asperistaltic pumps; in the example of FIG. 1 , a blood pump 21 isincluded on the blood withdrawal line 6.

The apparatus of the above-described embodiment may also comprise a userinterface 22 (e.g. a graphic user interface or GUI) and a control unit12, i.e. a programmed/programmable control unit, connected to the userinterface.

A bypass line 23 connects the dialysis fluid supply line 8 and thedialysis effluent line 13, thereby bypassing the filtration unit 2, andone or more fluid check members 24 connected to the control unit 12selectively opens and closes the bypass line 23.

A dialysis fluid pump 25 and a dialysate pump 26 may be included,located respectively on the dialysis fluid supply line 8 and on thedialysis effluent line 13 and further operatively connected to thecontrol unit 12.

The apparatus may also comprise a dialysis fluid source such as one ormore bags of fresh fluid (e.g. in CRRT treatment) or a dialysis fluidpreparation device 9 (e.g. in chronic treatment), which may be of anyknown type, for example including one or more concentrate sources 27, 28and respective concentrate pumps 29, 30 (regulating means 10) for thedelivery, as well as at least a conductivity sensor 35.

Due to the dialysis apparatus potentially comprising various liquidsources (e.g. one or more water sources 14, one or more concentratesources 27, 28, one or more sources 33 of disinfectant liquids)connected to the dialysis supply line 8 with respective delivery lines36, 37, 38 and 40, the apparatus may exhibit, at each delivery line, arespective check member (not all are shown in FIG. 1 ) and, for example,comprising a valve member 31 and 34.

Arranged in the dialysis supply line 8, in the direction in which theliquid circulates, there are the first flow meter 41 and the dialysisfluid pump 25.

The dialysis effluent line 13 may be provided with a dialysate pump 26and a second flow meter 42. The first and second flow meters 41, 42 maybe used to control (in a known manner) the fluid balance of a patientconnected to the blood circuit 17 during a dialysis session.

A sensor 11 is provided on the dialysis effluent line 13, immediatelydownstream the filtration unit 2, to measure a parameter value (e.g.conductivity) of the dialysate in the dialysis effluent line 13.

One or more infusion lines 39 may also be included, with respectiveinfusion pumps 43 or flow regulation valves, the infusion lines beingconnected up to the blood return line 7 and/or the blood withdrawal line6 and/or directly to the patient. The liquid sources for the infusionlines may be pre-packaged bags 44 and/or liquids prepared by theapparatus itself. The infusion line 39 may either receive infusionliquid from a pre-packaged bag 44 (solid line 45 a) or from an onlinepreparation through-branch 45 b (dotted line).

As already mentioned, the described embodiments are intended to benon-limiting examples.

In FIG. 1 , the blood return line 7 may be provided with a bag 100 forcirculating fluids therein (a bag embodiment is represented in FIG. 4 )before returning blood to the patient.

The extracorporeal blood treatment machine is provided with an apparatus300 for e.g. warming fluids circulating in the bag in order to regulatea temperature of the blood returned to the patient to a desiredtemperature region, for example around 37° C.

In the following description, reference is made to a fluid warmingapparatus to regulate blood temperature and to a corresponding warmingbag. However, the description should not be interpreted in a limitativeway in this respect. An apparatus for temperature fluid control isincluded in the scope of the appended claims. A bag for either warmingor cooling is also encompassed by the present description and claims.

Fluid warming apparatus 300 is generally designed to regulate thetemperature of (e.g. to warm) medical fluids such as blood orinfusion/substitution liquid. Fluid warming apparatus 300 may beemployed to warm medical fluids other than blood intended to be returnedor fluids intended to be supplied to the body of a patient, for examplewhen regulating the temperature of treatment solution enteringfiltration unit 2. In other terms, the bag 100 may be differentlyconnected to the dialysis line 8. Thus, fluid warming apparatus 300 maybe employed in a manner other than that illustrated in FIG. 1 . In theillustrative embodiment shown in FIG. 1 , fluid warming apparatus 300 isemployed to warm the blood being returned to the patient and coming fromair separator 19. An air detector 46 and a clamp 20 may be arranged onblood line 7 downstream from the fluid warming apparatus 300 andupstream from vascular access 18.

Given the above description of a possible embodiment of extracorporealblood treatment apparatus, thereafter specific embodiments of theapparatus 300 for e.g. warming fluids and of a bag 100 for fluids aredescribed.

FIG. 2 shows, schematically and in partially exploded view, an apparatus300 for warming fluids in accordance with embodiments of the presentinvention. Fluid warming apparatus 300 may generally be designed asshown, namely configured to e.g. substantially horizontally receive, ina slot 306, a bag 100 for e.g. warming fluids between a first 302 and asecond 304 component, defining a heating region 308 between the first302 and second 304 components. The apparatus 300 may be designed withfirst 302 and second 304 components pivotably connected to one another,thereby facilitating cleaning of heating region 308. First 302 andsecond 304 components may, however, also be connected to one another inany other suitable manner (e.g. disconnection, shifting, tilting),thereby facilitating cleaning and/or insertion/removal of bag 100. Inthe embodiment shown, first 302 and second 304 components are shownseparated from one another for clarity. During use, first 302 and second304 components are fixedly mounted to one another, thereby providingslot 306 for insertion/removal of bag 100. As shown, a bag 100 may beinserted into slot 306 and, thus, positioned in superimposition with theheating region 308. Slot 306 may be provided with an extension 307 inorder to receive a matching portion 107 of bag 100. Portion 107 may bein the form of a small tab protruding from one side of the bag 100 (seeFIG. 8 a ) or triangular shaped as shown in FIGS. 2 and 4 . Further,extension 307 of slot 306 may be provided with a reference protrusion307 r configured to engage a corresponding reference opening 107 r inbag 100. Tab, extension 307 and/or reference protrusion 307 r aredesigned to ensure proper placement of bag 100 into slot 306 asdescribed with respect to bag 100 further below.

The heating region 308 typically comprises heating surfaces betweenwhich, during use, a bag 100 is positioned, having a large portion ofits outer surfaces in contact with the heating surfaces. As shown inFIG. 2 , a bag 100 would present substantially flat upper 108-1 andlower 108-2 surfaces that may be brought into superimposition withcorresponding upper 308-1 and lower 308-2 (e.g. upper and lower) heatingsurfaces of heating region 308.

FIG. 3 shows a bag 100 k for warming fluids in accordance with a priorart design. The bag 100 k may generally be used with an apparatussimilar or identical to apparatus 300 for warming fluids as shown inFIG. 2 and as described above.

According to the prior art design, bag 100 k is made from two adjacentlayers of film material, for example plastic film, that are welded toone another in a specific manner in order to form a conduit for fluid tobe heated. The conduit puts an inlet port 112 k into fluid communicationwith an outlet port 116 k. The conduit further includes an inlet section113 k adjacent to inlet port 112 k and an outlet section 117 k adjacentto outlet port 116 k. As shown in FIG. 3 , the conduit further includesthree deflection sections 110 k, connecting the elongated sections ofbag 100 k with one another and, respectively, with the inlet section 113k and the outlet section 117 k, providing the conduit with a generallymeandering shape.

As shown in FIG. 3 , inlet section 113 k, deflection sections 110 k,outlet section 117 k, and elongated sections in between typically havesubstantially the same cross-section, with little or no variation in thewidth and/or cross-section of the conduit over any of the sections.

The direction of fluid flow F is shown in FIG. 3 for each of theelongated sections and is generally directed from the inlet port 112 ktowards the outlet port 116 k. As illustrated, fluid flowing through theconduit from inlet port 112 k towards outlet port 116 k enters theconduit at the inlet section 113 k and exits the conduit at outletsection 117 k. The fluid is also deflected according to the meanderingshape of the conduit at the deflection sections 110 k. The fluid flowprofile through the conduit is dependent on the geometry of the conduitin the respective sections (e.g. inlet section, outlet section,elongated section(s), deflection section(s)), flow rate and viscosity.While the fluid flow is relatively fully developed over the elongatedsections, it varies with respect to a number of fluid flow parametersthroughout the sections of the conduit.

As can be seen from FIG. 3 , fluid flow through the conduit exhibitsregions A of fluid flow having a relatively lower velocity or evenstagnating, regions B of relatively homogeneous fluid flow, and regionsC of fluid flow having relatively higher velocity.

Low velocity fluid flow may entail substantial disadvantages, forexample areas with little or no exchange of fluid due to the formationof stagnation areas and/or to the collection or accumulation of airbubbles in areas of low fluid flow. If the fluid conveyed through theconduit is blood, low velocity fluid flow may lead to clotting,entailing the risk of blood clots being created, being carried away bythe blood flow, and ultimately being returned to the patient in theblood flow. This is particularly likely in case of stagnation of fluid,when regions are formed in which little or no fluid flow occurs andwhere little to none exchange of fluid with the mass of fluid flowingthrough the conduit takes place. Low velocity fluid flow is, thus, to beavoided.

Low velocity fluid flow, denoted in FIG. 3 as regions A, may occur atthe inlet section 113 k, at the outlet section 117 k, and at thedeflection section 110 k. The shape of the deflection sections 110 k maysignificantly contribute to the formation of low velocity fluid flow, inparticular in the intermediate section thereof (see region A along anouter edge of the intermediate section) and in the exit section thereof(see region A located at an inner edge of the exit section, downstreamfrom the intermediate section).

High velocity fluid flow may also entail disadvantages, for exampleexcessive pressure drop between the inlet and the outlet of thecontainer and high shear stress in the near container wall vicinity.

High velocity fluid flow, denoted in FIG. 3 as regions C, may occur nearthe inlet section 113 k, near the outlet section 117 k, and at thedeflection section 110 k. High velocity fluid flow, occurring near theinlet section 113 k or near the outlet section 117 k is typically lesscritical, since the higher velocity is generally caused by the fluidflowing from medical tubing through the inlet port 112 k (or towards theoutlet port 116 k), which is typically provided with a smallercross-section than that of the conduit. However, high velocity fluidflow occurring near the inlet section 113 k or near the outlet section117 k may have detrimental effects as well.

The shape of the fluid path geometry (in combination with fluid flowrate and viscosity) causes low/high velocity regions for the fluid. Highvelocity fluid flow occurring at the deflection section 110 k typicallyoccurs at an inner edge of the intermediate section thereof. Excessivelyhigh velocity fluid flow is to be avoided since it may cause bloodhaemolisis.

FIG. 4 shows a bag 100 for an apparatus 300 for warming fluids, the bag100 being in accordance with a first embodiment of the presentinvention. FIG. 8A shows a second embodiment of bag 100 particularlydesigned for high flow rates. The bag 100 is flexible and in particularmade of a film material.

The bag 100 may be made from two layers of film material, particularlypolyurethane (PUR) or polyvinylchloride (PVC), superposed and welded toform the bag 100 and to form a conduit delimited by the two layers andby the lines of welding. Lines of welding are not shown in FIG. 4 forclarity. For illustration purposes, lines of welding 120 are shown inthe detailed view of FIG. 5 .

Polyurethane (PUR) is a material having high mechanical resistance andgood thermal transfer properties. Therefore, the use of PUR may providebag 100 with advantageous properties regarding heat transfer through thefilm material and to the fluid inside bag 100. The use of PUR mayfurther minimize the risk of leakage of fluid from bag 100.

The embodiment shown in FIG. 4 is provided with four connection sections102 arranged substantially parallel to one another in a layoutexhibiting a substantially side-by-side arrangement of the fourconnection sections 102.

Vice versa, the embodiment shown in FIG. 8A is provided with twoconnection sections 102 only. It is noted that the connection sections102 are shown as parallel to an overall development direction of bag 100(e.g. substantially parallel to directions F and/or the direction offluid inflow and outflow—see arrows near element 111). However,connection sections 102 may be arranged at an angle (e.g. orthogonal)with respect to the overall development direction and/or with respect toone another. In the latter case, the cross-section and/or maximum widthL_(c) of the conduit may increase or decrease to a certain extent alongthe length of any of the sections (e.g. connection sections, deflectionsections, etc.).

The terms width and cross-section both pertain to a measure of crosssectional size of the conduit and its sections and are used to reflectthe different states of bags 100 before and during use. As the bags 100are made of layers of plastic film, a bag has, before use, asubstantially flat shape, due to the conduit not containing any liquidor particles. In this unused state, the size of the conduit may bereferred to as having a width, since the width of the flat conduit is aneffective measure thereof. During use, however, the fluid being conveyedthrough the conduit causes the two layers of film to cease contactingeach other, thereby opening up the conduit vertically and facilitatingfluid flow. In this used state, the size of the conduit may be referredto as having a cross-section, since the cross-section (or cross sectionarea) is an effective measure thereof. Typically, in one embodiment(FIG. 4 ) the cross section of the conduit has, during use, a size ofapproximately 1-2 mm (height)×18-22 mm (width), in particular about 1.4mm×20 mm. The width or maximum width L_(c) of the conduit, when the bagis not used (i.e. flat), is approximately 20 mm. In some embodiments(FIG. 8A), the cross section of the conduit may be larger; the crosssection of the conduit has, during use, a size of approximately 1-2 mm(height)×34-45 mm (width), in particular about for example 1.4 mm×40 mm,for high flow applications. It is noted that the main principles of theoverall design, in particular those of having a conduit with a widththat is much larger than its height (i.e. substantially 2D flow withwidth>>height) and the conduit being designed for laminar flow, may beapplied in a broad range of applications and is not restricted to thedimensions given (e.g. with respect to the application for blood warmerbags). In this respect several properties may be adjusted for individualapplications, for example the relation between the heat exchange surfacearea with respect to a target performance (e.g. W×L, conduitwidth×conduit length), minimum/maximum shear rates in the target flowoperating range (e.g. depending on width and height of the conduit), andpressure drop (e.g. depending on width, height, and length of theconduit).

In this respect when referring to 2D flow, it is intended that the fluidflows in a channel having a width much higher than the height so that,though being of course the flow three dimensional, it may be consideredsubstantially bi-dimensional. In more detail, the ratio between thewidth and the height is higher than 5 (L_(c)/h>5), possibly higher than10. The two examples of FIGS. 4 and 8A have a ratio L_(c)/h of more than10.

Moreover, the present bag embodiments are more advantageous in presenceof, though not limited, and particularly designed for laminar flowconditions inside the bag.

Generally referring to the disclosed embodiments (FIGS. 4 and 8A),opposite ends of the meandering conduit are arranged on the same side ofbag 100 and are provided with an inlet section 113 and an outlet section117. The inlet section 113 and the outlet section 117 are furtherconnected to an inlet port 112 and an outlet port 116, respectively. Theinlet 112 and outlet 116 ports may further include a tube or medicalfluid line 111 and/or a Luer connector (not shown). The Luer connectorsmay be arranged at an opposite end of the tubes 111. In particular tube111 connected to the inlet 112 may be provided with a male Luerconnector and tube 111 connected to the outlet 116 may be provided witha female Luer connector so to avoid erroneous connection of the bag 100to the extracorporeal blood circuit. In some embodiments, the Luerconnectors may be arranged adjacent to inlet port 112 and/or outlet port116, respectively. The tubes may also be made from, for example, PVC orPUR.

More generally, the inlet 112 is provided with a connector configured tobe coupled with a respective counter connector on the return line 7placed downstream the filtration unit 2 and possibly downstream the airseparator 19, but immediately upstream the warmer unit 300 and upstreamthe air detector 46; the outlet 116 is provided with a connectorconfigured to be coupled with a respective counter connector on thereturn line placed immediately downstream the warmer unit 300 andupstream the air detector 46; the inlet and outlet connectors and thecounter connectors are configured to be coupled only in the correctconfiguration (i.e. the inlet connector may not be coupled to the outletcounter-connector and the outlet connector may not be coupled to theinlet counter-connector).

Adjacent connection sections 102 are joined together and put in fluidcommunication by means of deflection sections 110. Deflection sections110 define rounded bends that provide the conduit with an overallmeandering (or serpentine) shape. Each deflection section 110 includes arespective entry section 110 e, a respective intermediate section 110 i,and a respective exit section 110 x, arranged in sequence based on fluidflow through the conduit (see arrows F in FIGS. 4 and 8A).

As shown in FIG. 4 and FIG. 8A, the entry section 110 e, theintermediate section 110 i, and the exit section 110 x of eachdeflection section 110 are provided with a specific shape in order toavoid one or more of the problems mentioned above associated with priorart designs. In the embodiments shown, the entry section 110 e providesthe conduit with a decrease in the maximum width (or internal diameter)from the adjacent connection section 102 (having a largerwidth/diameter) towards the adjacent intermediate section (having asmaller width/diameter). The exit section 110 x provides the conduitwith an increase in the maximum width (or internal diameter) from theadjacent intermediate section (having a smaller width/diameter) towardsthe adjacent connection section 102 (having a larger width/diameter).Intermediate section 110 i is shown as having a substantially constantwidth/diameter.

The individual shapes of entry section 110 e and exit section 110 x aredifferent from one another. Entry section 110 e includes an inner edge110 e-1 and an outer edge 110 e-2, inner and outer being defined withrespect to the corresponding intermediate section 110 i, which definesan outer edge 110 i-2 (i.e. the outside of the bend) and an inner edge110 i-1 (i.e. the inside of the bend). The inner edge 110 e-1 of entrysection 110 e is provided with a nonlinear shape (e.g. correspondingsubstantially to a segment of a circle) while the outer edge 110 e-2 ofentry section 110 e is provided with a straight shape (e.g. continuingstraight and in extension from the corresponding outer edge 102-2 of thepreceding connection section 102). The nonlinear shape of the inner edge110 e-1 of entry section 110 e determines the decrease inwidth/cross-section of the conduit from the preceding connection section102 to the following intermediate section 110 i.

With respect to the terms “inner edge” and “outer edge” in connectionwith connection sections 102, the following is noted. For connectionsections 102, which are provided to connect deflection sections 110 withone another, the terms “inner” and “outer” with respect to the edges ofa connection section 102 pertain to the respective nearest deflectionsection 110. FIG. 4 shows this naming convention for reasons of clarityonly for one of the two connection sections 102 provided for connectiondeflection sections 110 with one another (see the second and thirdconnection section 102 in direction of fluid flow F). In direction offluid flow F, the third connection section 102 is provided withreference numerals showing the respective inner and outer edges thereof.Thus, the top edge (i.e. the edge closer to the top of FIG. 4 ) of thethird connection section 102 is marked as inner edge 102-1 near thesecond deflection section 110 (in direction of fluid flow F, andadjacent to identification region 109). The bottom edge (i.e. the edgecloser to the bottom of FIG. 4 ) of the third connection section 102 ismarked, along the same section of the conduit, as outer edge 102-2 nearthe second deflection section 110.

Correspondingly, the top edge of the third connection section 102 ismarked as outer edge 102-2 near the third deflection section 110 (indirection of fluid flow F, and adjacent to portion 107). The bottom edgeof the third connection section 102 is marked, along the same section ofthe conduit, as inner edge 102-1 near the third deflection section 110.In this manner, the terms “inner” and “outer” always correspond to thenearest deflection section 110. Therefore, the terms “inner” and “outer”change in direction of fluid flow F along the conduit depending on thenearest deflection section 102, thereby clearly identifying the portionsof connection sections 102 which are referred to as inner 102-1 andouter 102-2 edges.

It is noted that the above also applies to the remaining connectionsections 102, which are provided to connect deflection sections 110 toone another (i.e. it applies also to the second connection section 102shown in FIG. 4 ). Not all reference numerals have been added to FIG. 4, however, for reasons of clarity. It is further noted that the abovealso applies in embodiments having fewer or more connection sections 102than the embodiment shown in FIG. 4 (e.g. having 2 or 6 or moreconnection sections 102).

In both embodiments of FIGS. 4 and 8A, similar to entry section 110 e,exit section 110 x includes an inner edge 110 x-1 and an outer edge 110x-2, inner and outer being defined with respect to the correspondingintermediate section 110 i in the same manner as described with respectto entry section 110 e above. The inner edge 110 x-1 of exit section 110x is provided with a substantially linear shape (e.g. substantiallycorresponding to a line segment positioned at an angle with respect tothe corresponding edge of the following connection section 102) whilethe outer edge 110 x-2 of exit section 110 x is provided with a straightshape (e.g. leading straight and in extension to the corresponding edgeof the following connection section 102). The angular configuration ofthe inner edge 110 x-1 of exit section 110 x with respect to thecorresponding edge of the adjacent (following) connection section 102determines the increase in width/cross-section of the conduit from theintermediate section 110 i to the following connection section 102.

In the embodiment shown in FIG. 4 , the conduit of bag 100 includesthree deflection sections 110. All deflection sections 110 aresubstantially identical to one another, apart from having amirror-inverted layout depending on the deflection section 110determining a right turn or a left turn (in direction of fluid flow andas seen from the top; see FIG. 4 ). Thus, the description of entrysections 110 e, intermediate sections 110 i, and exit sections 110 x isapplicable to any one of the deflection sections 110 shown in FIG. 4 .It is noted that, depending upon the deflection section 110 determininga right turn or a left turn, the positions of “inner” and “outer” edgeschanges accordingly, so that with respect to the connection sections 102the terms “inner” and “outer” receive their respective meaning inrelation to the deflection section 110, which is referred to in therespective context (i.e. based on a respective inlet end or outlet endof a connection section 102).

As can be seen from FIG. 4 (and similarly for embodiment of FIG. 8A),the fluid flow through the conduit defined by bag 100 is ratherhomogeneous. At the intermediate sections 110 i of the deflectionsections 110, there is little to no stagnation or regions of lowvelocity fluid flow. This is achieved by a moderate overall increase influid flow velocity in the intermediate sections 110 due to the decreasein width/cross-section in the respective entry section 110 e, which ismaintained throughout the intermediate section 110 i. Further, theregion of high velocity fluid flow (see region C—FIG. 4 ) is lessfocused/localized and spreads across a longer and wider portion of thedeflection section 110. This reduces or minimizes shear stress andcauses the high velocity fluid flow in region C to be more homogeneous.

Another effect of the individual configuration of the deflectionsections 110 is that there is little to no low velocity fluid flow (andno stagnation) in the respective exit sections 110 x of the deflectionsections 110. This is achieved both by the particular configuration ofthe exit section 110 x and by the less focused/localized and morespread-out region C of high velocity fluid flow throughout theintermediate sections 110 i.

The ratio between the width/cross-section of the connection sections 102and the width/cross-section of intermediate sections 110 ranges between0.5 and 0.85, particularly between 0.7 and 0.8.

Tests have been conducted with different fluid flow rates. At lower flowrates of, for example, 100 ml/min, the effect of the individualconfiguration of the deflection sections 110 in line with the embodimentshown in FIG. 4 is more pronounced. However, the effect may also besignificant as compared to known designs at higher fluid flow rates of,for example, 200 ml/min or 300 ml/min, at which the beneficial effectsdescribed above also continue to occur.

The bag 100 in accordance with the present invention may further includeinlet 113 and outlet 117 sections configured to improve fluid flowthrough the conduit. In some embodiment either one or both of inlet port112 and outlet port 116 may be arranged excentrically with respect to amain development axis of the adjacent connection section 102.

In the embodiment shown in FIGS. 4 and 8A, inlet port 112 and outletport 116 are arranged excentrically with respect to the respectiveconnection section 102 respectively putting the inlet 113 and outlet 117sections in fluid communication with the following/preceding deflectionsection 110. In the embodiment of FIG. 4 , inlet port 112 is arrangedsubstantially parallel to the adjacent connection section 102 andslightly (laterally) shifted towards the center of bag 100 (e.g. towardsand parallel to outlet port 116). In the embodiment of FIG. 8A, inletport 112 is arranged substantially parallel to the adjacent connectionsection 102 and slightly (laterally) shifted away from the center of bag100 (e.g. away from and parallel to outlet port 116).

In accordance with this placement of the inlet port 112, inlet section113 is provided with an asymmetrical configuration, presenting an inneredge 113-1 and an outer edge 113-2, both positioned at an angle withrespect to an axis 112 c of inlet port 112. Angles 11313 and 113 a ofthe inner 113-1 and outer 113-2 edges may be different from one anotheror the same. In some embodiments, due to the inlet port 112 not beingcentered with respect to the adjacent connection section 102, the inner113-1 and outer 113-2 edges of inlet section 113 may have differentlengths, even if angles 1138 and 113 a are the same. Inlet section 113provides the conduit with a diverging region, increasing thewidth/cross-section of the conduit from the diameter of the inlet port112 to the cross-section of the adjacent connection section 102.

The outlet section 117 is provided with inner 117-1 and outer 117-2edges in a similar manner as described with respect to inlet section 113above. In the embodiment of FIG. 4 , outlet port 116 is arrangedsubstantially parallel to the adjacent connection section 102 andslightly (laterally) shifted towards the center of bag 100 (e.g. towardsand parallel to inlet port 112). In the embodiment of FIG. 8A, outletport 116 is arranged substantially parallel to the adjacent connectionsection 102 and slightly (laterally) shifted away from the center of bag100 (e.g. away from and parallel to inlet port 112)

In accordance with this placement of the outlet port 112, outlet section117 is provided with an asymmetrical configuration, presenting an inneredge 117-1 and an outer edge 117-2, both positioned at an angle withrespect to a central axis 116 c of port 116. The angles 11713 and 117 aof the inner 117-1 and outer 117-2 edges may be different from oneanother or the same. Due to the outlet port 116 not being centered withrespect to the adjacent connection section 102, inner 117-1 and outer117-2 edges may have different lengths, even if angles 117 a and 11713are the same. Outlet section 117 provides the conduit with a convergingregion, decreasing the width/cross-section of the conduit from thecross-section of the adjacent connection section 102 to the diameter ofthe outlet port 116.

Additionally, the inlet 113 and outlet 117 sections are provided withdifferent shapes due to the direction of fluid flow being different forthe two sections. In other words, the diverging region of inlet section113 has a shape different from the converging region of the outletsection 117 (see FIGS. 4 and 8C).

In both embodiments, the inlet section 113 is provided with inner 113-1and outer 113-2 edges that form a smaller angle with respect to thecorresponding edge of the adjacent connection section 102 thancorresponding angles formed by inner 117-1 and outer 117-2 edges ofoutlet section 117. It was found that regions A exhibiting lowervelocity fluid flow at the inlet section 113 (see corresponding inletsection 113 k in FIG. 3 for comparison) may be substantially reduced byproviding the inlet section 113 with a gradually increasing (w.r.t.direction of fluid flow) width/cross-section that increases thewidth/cross-section over a longer distance of fluid flow through theconduit.

Likewise, regions A exhibiting lower velocity fluid flow at the outletsection 117 (see corresponding outlet section 117 k in FIG. 3 forcomparison) may be substantially reduced by providing the outlet section117 with a gradually decreasing (w.r.t. direction of fluid flow)width/cross-section that decreases the width/cross-section over ashorter distance of fluid flow through the conduit. The reduction ofregions A exhibiting lower velocity fluid flow at both the inlet 113 andoutlet 117 sections was most pronounced in combination with theasymmetrical arrangement of inlet 112 and outlet port 116 as shown inFIGS. 4 and 8C.

In some embodiments, two layers of plastic film (e.g. PUR or PVC) form aportion 107, located on the side of bag 100 opposite to the inlet/outletports and adjacent to the conduit. The portion 107 may be in the form ofa tab (FIG. 8A) emerging from a lateral area on the side opposite toinlet/outlet; alternatively the portion may be optionally triangular asshown in the annexed FIG. 4 by way of non-limiting example. The portion107 is designed to fit into a correspondingly counter-shaped portion ofslot 306 of the fluid warming apparatus 300. In some embodiments, theportion 107 is provided with a reference opening 107 r. Referenceopening 107 r is designed to fit with a corresponding protrusionprovided in slot 306 of the fluid warming apparatus 300. Triangularportion 107 and/or reference opening 107 r are positioned with respectto remaining components of bag 100 in order to ensure proper placementof bag 100 into slot 306 of the fluid warming apparatus 300. In someembodiments, bag 100 is inserted into apparatus 300 generally alonginsertion direction G.

Alternatively (or in combination) a sensor, e.g. an optical sensor) maybe used to sense the presence of the bag 100, i.e. to sense the presenceof the (tab/triangular) portion 107.

Proper placement includes, for example, inlet/outlet tubes engaged incorresponding recesses and the conduit being placed in superimpositionwith heating region 308.

Bag 100 may further include, particularly in an identification region109 between inlet 112 and outlet 116 ports, which is not occupied byportions of the conduit, an area configured for placing a machine- orhuman-readable label, indicating, for example, properties of bag 100.

FIG. 5 and corresponding FIG. 8B show a respective deflection section110 of one or more deflection sections 110 as used in a bag 100 for anapparatus for warming fluids 300 as described above, the bag 100 beingin accordance with an embodiment of the present invention. FIGS. 5 and8B illustrates possible measurements for different elements of theconduit. It is noted, however, that the measurements shown are exemplaryand not intended to limit the embodiments described herein.

Welding lines 120 typically have a width of about 2 mm to about 4 mm,particularly about 3 mm. The conduit according to FIGS. 4 and 5typically has a width of about 20 mm along the connection sections 102.As described with respect to FIG. 4 above, entry sections 110 e ofdeflection sections 110 typically reduce the width of the conduit fromabout 20 mm to about 15 mm in the intermediate sections 110 i. To thisaim, entry sections 110 e may have an inner edge 110 e-1 correspondingto a segment of a circle having a radius of e.g. about 10 mm (see FIG. 5—R₁). The circle segment of the inner edge 110 e-1 of the entry section110 e then continues into the inner edge 110 i-1 of the intermediatesection 110 i, which is defined by a segment of a circle having a radiusR₂ of e.g. about 4-5 mm (see FIG. 5 ). The intermediate section 110 ihas a width of about 15 mm (see above) and the outer edge 110 i-2thereof is defined by a radius R₃ of e.g. about 21.5 mm (see FIG. 5 ).The exit section 110 x has a length in direction of fluid flow F ofabout 30 mm and is defined by an outer edge 110 x-2 continuingtangentially from the outer edge of the intermediate section 110 i andan inner edge 110 x-1 positioned at an angle 110 x-1 a of e.g. about10.26° with respect to a main development axis of the followingconnection section 102 (e.g. an inner/outer edge thereof). In both thefirst and second embodiments, the outlet diverging angle, that is theangle between the inner edge 110 x-1 and the corresponding edge of theconnection section 102, is less than 25°, particularly less than 15°.

FIG. 5 illustrates the asymmetrical configuration of a deflectionsection 110 according to embodiments of the present invention, as wellas the welding lines 120 providing bag 100 with a conduit of thecorresponding shape.

The conduit according to FIGS. 8A to 8C typically has a width of about40 mm along the connection sections 102. As described, entry sections110 e of deflection sections 110 typically reduce the width of theconduit from about 40 mm to about 30 mm in the intermediate sections 110i. To this aim, entry sections 110 e may have an inner edge 110 e-1corresponding to a segment of a circle having a radius of e.g. about 10mm (see FIG. 5 , R₁). The circle segment of the inner edge 110 e-1 ofthe entry section 110 e then continues into the inner edge 110 i-1 ofthe intermediate section 110 i, which is defined by a segment of acircle having a radius of e.g. about 6.5 mm (see FIG. 5 , R₂). Theintermediate section 110 i has a width of about 30 mm (see above) andthe outer edge 110 i-2 thereof is defined by a radius of e.g. about 44.5mm (see FIG. 5 , R₃). The exit section 110 x has a length in directionof fluid flow F of about 40 mm and is defined by an outer edge 110 x-1continuing tangentially from the outer edge of the intermediate section110 i and an inner edge 110 x-2 positioned at an angle 110 x-1 a of e.g.about 14° with respect to a main development axis of the followingconnection section 102 (e.g. an inner/outer edge thereof). In both thefirst and second embodiments, the outlet diverging angle, that is theangle between the inner edge 110 x-2 and the corresponding edge of theconnection section 102, is less than 25°, particularly less than 15°.

FIG. 6A shows a side view of an inlet section 113 in accordance withembodiments of the present invention. FIG. 6A illustrates a keyparameter in transitioning the diameter 112 d of the inlet port 112 (ordirectly of the tubing 111) to the height h of the connection sections102, namely parameter a describing an angle between a plane parallel toa longitudinal extension of connection sections 102 and a connectingsection adjacent to the inlet port 112 or the tubing 111. Due to thediameter of the tubing 111 or of the inlet port 112 being larger thanthe height h of the connection sections 102, the two opposite layersdefining the sides of the inlet section have an angular configuration inwhich angle ‘a’ determines over which distance, in direction of fluidflow F, the substantially circular diameter 112 d of the inlet port 112or tubing 111 is adapted to the substantially flat cross section of theconnection sections 102 (e.g. having a height h much smaller than themaximum width Lc). FIG. 6A illustrates an angle ‘a’ of about 4°,resulting in the substantially circular diameter 112 d of the inlet port112 being adapted slowly (e.g. over substantially the entire inletsection 113) to the substantially flat cross section of the connectionsections 102 (un-pinched situation).

FIG. 6B shows a perspective view of an inlet section 113 in accordancewith embodiments of the present invention. FIG. 6B illustrates an angle‘a’ of about 10°, resulting in the substantially circular diameter 112 dof the inlet port 112 being adapted more quickly than as shown in FIG.6A (e.g. over a shorter section inlet section 113) to the substantiallyflat cross section of the connection sections 102. In other terms, FIG.6B shows a situation in which the inlet section is pinched incorrespondence of the second portion 113-2 where the two surfaces becomeparallel. As can be seen from FIGS. 6A and 6B, the correspondingsections of the inlet section 113 (or portions thereof) depend on thevalue of the angle ‘a’ and, thus, do not have to be limited to anextension of the inlet section 113 itself. FIG. 6B shows that the inletsection 113 has one portion 113-1 in which opposing layers of materialare at an angle ‘a’ with respect to a plane parallel to the connectionsections 102 (not shown) and another portion 113-2 in which the opposinglayers are substantially parallel and at a distance substantiallycorresponding to the height h of the connection sections 102. Generally,the angle ‘a’ may be modified to determine the manner in which fluidentering the container 100 at the inlet port 112 is being spreadlaterally to conform to the substantially flat cross section of theconnection sections 102. Here, a larger angle ‘a’ may lead to the fluidbeing spread laterally more quickly or effectively (e.g. along a shorterdistance in direction of fluid flow F) in order to reduce or eliminatethe formation of regions A of fluid flow having a relatively lowervelocity.

Generally, the angle ‘a’ may be modified to determine the manner inwhich fluid entering the container 100 at the inlet port 112 is beingspread laterally to conform to the substantially flat cross section ofthe conduit sections 102. Here, a larger angle ‘a’ may lead to the fluidbeing spread laterally more quickly or effectively (e.g. along a shorterdistance in direction of fluid flow F) in order to reduce or eliminatethe formation of regions A of fluid flow having a relatively lowervelocity.

FIGS. 7A to 7D show fluid flow based on different alternativeembodiments of inlet sections in accordance with embodiments of thepresent invention. FIGS. 7A to 7D illustrate the influence of the angle‘a’ on the fluid dynamics and, in particular, on the formation ofregions A and C indicating regions of fluid flow having respectivelyrelatively lower and higher velocity (e.g. contours of the velocitymagnitude). FIG. 7A shows a fluid flow simulation for angle ‘a’=4°, FIG.7B shows a fluid flow simulation for angle ‘a’=5°, FIG. 7C shows a fluidflow simulation for angle ‘a’=10°, and FIG. 7D shows a fluid flowsimulation for angle ‘a’=15°. As can be seen, each angle α and eachassociated configuration of the respective inlet section 113 influencesthe fluid flow through the inlet section and, in particular, theformation of regions A and C as described above. It is noted that theexamples shown in FIGS. 7A to 7D are based on the same fluid having aspecific viscosity and being conveyed at the same fluid flow rate forreasons of comparison of different configurations for inlet sections113. The pressure drop for the examples of FIGS. 7A to 7D wassubstantially the same with 3133 Pa, 3152 Pa, 3182 Pa, and 3208 Pa,respectively.

While the invention has been described in connection with what ispresently considered to be the most practical embodiment, it is to beunderstood that the invention is not to be limited to the disclosedembodiment, but on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andthe scope of the appended claims.

The invention claimed is:
 1. A container for enabling fluid flow,wherein the container comprises a flexible bag with at least a first anda second film sealed to one another, the container comprising: an inletport; an outlet port; and a fluid conduit to put the inlet port in fluidcommunication with the outlet port and comprising one or more deflectionsections, wherein the fluid conduit has a maximum width in a directionof the fluid flow through the fluid conduit, wherein at least one of theone or more deflection sections further comprises an entry section andan exit section, each respective exit section being arranged downstream,in the direction of the fluid flow, from each respective entry section,wherein a width of the fluid conduit decreases along the direction ofthe fluid flow through the entry section over a first distance, from themaximum width to a narrower width and the width of the fluid conduitconstantly increases along the direction of the fluid flow through theexit section over a second distance, from the narrower width to themaximum width, and wherein the first distance is between 0.5 and 0.7times the maximum width of the fluid conduit and the second distance isbetween 1.0 and 2.0 times the maximum width of the fluid conduit.
 2. Thecontainer according to claim 1, wherein the first distance is smallerthan the second distance.
 3. The container according to claim 1, wherein${0.5 \leq \frac{L_{t}}{L_{c}} \leq 0.85},$ and wherein L_(t) is a widthof an intermediate section located between the entry and exit sectionsand L_(c) is the maximum width.
 4. The container according to claim 1,wherein the width of the fluid conduit decreases along the direction ofthe fluid flow through the entry section according to a first radius ofcurvature in a first phase of the entry section and according to asecond radius of curvature in a second phase of the entry section,wherein the first radius of curvature is different than the secondradius of curvature.
 5. The container according to claim 1, wherein themaximum width is between 18 and 22 millimeters.
 6. The containeraccording to claim 1, wherein, for each of the one or more deflectionsections, the entry section has a first end and a second end, the firstend of the entry section being upstream, in the direction of the fluidflow, of the second end of the entry section, wherein the exit sectionhas a first end and a second end, the first end of the exit sectionbeing upstream, in the direction of the fluid flow, of the second end ofthe exit section, and wherein the width of the fluid conduit at thefirst end of the entry section is equal to the width of the fluidconduit at the second end of the exit section.
 7. The containeraccording to claim 1, wherein each of the one or more deflectionsections further comprises an intermediate section interposed betweenthe entry section and the exit section, wherein each respectiveintermediate section: has a constant width equal to the narrower width,is directly adjacent to the corresponding entry section, thecorresponding entry section being a direct extension of the respectiveintermediate section, and is directly adjacent to the corresponding exitsection, the corresponding exit section being a direct extension of therespective intermediate section, wherein the fluid conduit is providedwith an inner radius R₂ calculated as${R_{2} = {{\left( {1 - \frac{L_{t}}{L_{c}}} \right) \cdot L_{c}} + \frac{weld}{2}}},$ with L_(c)=the width, L_(t)=the width of the intermediate section, andweld=width of a weld, wherein the ratio $\frac{R_{2}}{L_{c}}$  betweenthe inner radius R₂ and the width ranges from 0.15 to 0.50, and whereinthe fluid conduit is provided with an outer radius R₃, wherein$R_{3} = {L_{c} + {\frac{weld}{2}.}}$
 8. The container according toclaim 7, wherein the intermediate section has an inner edge and anopposite outer edge, the inner edge having a radius smaller than aradius of the outer edge, and wherein each of the entry section and theexit section has a respective inner edge in extension to the inner edgeof the intermediate section and wherein each of the entry section andthe exit section has a respective outer edge in extension to the outeredge of the intermediate section, wherein the width of the fluid conduitdecreases along the direction of the fluid flow through the entrysection due to a directional change of the inner edge of the entrysection, the outer edge of the entry section continuing straight ortangentially in extension from the outer edge of the intermediatesection, and wherein the width of the fluid conduit increases along thedirection of the fluid flow through the exit section due to adirectional change of the inner edge of the exit section, the outer edgeof the exit section continuing straight or tangentially in extensionfrom the outer edge of the intermediate section.
 9. The containeraccording to claim 7, wherein the intermediate section is provided witha deflection of at least 180°.
 10. The container according to claim 1,wherein the width of the fluid conduit decreases along the direction ofthe fluid flow through the entry section due to a directional change ofan inner edge of the entry section, wherein an outer edge of the entrysection is straight, and wherein the width of the fluid conduitincreases along the direction of the fluid flow through the exit sectiondue to a directional change of an inner edge of the exit section,wherein an outer edge of the exit section is straight.
 11. The containeraccording to claim 1, wherein the fluid conduit further comprises aplurality of connection sections, wherein, along each of the pluralityof connection sections, the width is constant, wherein the fluid conduitalong each of the plurality of connection sections is straight, andwherein the plurality of connection sections comprises an inlet sectionconnected to the inlet port and to an adjacent first connection sectionof the plurality of connection sections, the inlet section providing thefluid conduit with a transition from a diameter of the inlet port to themaximum width of the fluid conduit at the first connection section. 12.The container according to claim 11, wherein the inlet section includesan inner edge and an outer edge, the inner edge and the outer edge eachforming a respective inlet angle with respect to an axis of the inletport of 5° to 30°.
 13. The container according to claim 11, wherein theplurality of connection sections comprises an outlet section connectedto the outlet port and to an adjacent second connection section of theplurality of connection sections, the outlet section providing the fluidconduit with a transition from a diameter of the outlet port to thewidth of the fluid conduit at the second connection section, the outletsection including an inner edge and an outer edge, the inner edge andthe outer edge each forming a respective outlet angle with respect to anaxis of the outlet port of 25° to 60°.
 14. The container according toclaim 1, wherein the one or more deflection sections includes a numberof deflection sections, the number of deflection sections being uneven,wherein the number of deflection sections is equal to 3, 5, 7 or
 9. 15.The container according to claim 1, further comprising a proximal endand a distal end opposite the proximal end, wherein both the inlet portand the outlet port are arranged at the proximal end.
 16. The containeraccording to claim 1, wherein the inlet port is configured forconnecting to a fluid inlet line of a blood treatment apparatus and forreceiving medical fluid from the fluid inlet line through the inletport, wherein the outlet port is configured for connecting to a fluidoutlet line of the blood treatment apparatus and for releasing themedical fluid from the outlet port into the fluid outlet line.
 17. Thecontainer according to claim 1, wherein a ratio between the maximumwidth of the fluid conduit over a maximum height of the fluid conduit isgreater than
 10. 18. The container according to claim 1, wherein thecontainer is made from a flexible material including one or more ofpolyurethane and polyvinylchloride.
 19. A container for enabling fluidflow, the container comprising: an inlet port; an outlet port; and afluid conduit to put the inlet port in fluid communication with theoutlet port and comprising one or more deflection sections, wherein thefluid conduit has a maximum width in a direction of the fluid flowthrough the fluid conduit, wherein at least one of the one or moredeflection sections further comprises an entry section and an exitsection, each respective exit section being arranged downstream, in thedirection of the fluid flow, from each respective entry section, whereinfor each of the one or more deflection sections: the entry section has afirst end and a second end, the first end of the entry section beingupstream, in the direction of the fluid flow, of the second end of theentry section, the exit section has a first end and a second end, thefirst end of the exit section being upstream, in the direction of thefluid flow, of the second end of the exit section, and an intermediatesection interposed between the entry section and the exit section, theintermediate section having a constant width, the intermediate sectionbeing provided with a deflection of about 180°, wherein a width of thefluid conduit decreases along the direction of the fluid flow throughthe entry section over a first distance and the width of the fluidconduit increases along the direction of the fluid flow through the exitsection over a second distance, wherein the width of the fluid conduitdecreases along the direction of the fluid flow through the entrysection from the maximum width to a narrower width and the width of thefluid conduit increases along the direction of the fluid flow throughthe exit section from the narrower width to the maximum width, whereinthe width of the fluid conduit at the first end of the entry section isequal to the width of the fluid conduit at the second end of the exitsection and the constant width of the intermediate section is equal tothe narrower width, wherein the first distance is between 0.5 and 0.7times the maximum width of the fluid conduit and the second distance isbetween 1.0 and 2.0 times the maximum width of the fluid conduit,wherein the first distance is smaller than the second distance, andwherein the container is made from a flexible material and comprises abag having at least a first and a second film, the first and the secondfilms being sealed to one another.